A measuring system having a biophotonic sensor is a device that detects a specific antigen based upon the optical properties of the biophotonic sensor. In the biophotonic sensor, an antibody of an antigen is immobilized. When a blood plasma or a liquid containing the antigen is introduced to the biophotonic sensor, the antigen combines with the antibody in the biophotonic sensor, thereby changing the optical properties of the biophotonic sensor.
Below, it will be described of a process of producing the concentration of an antigen using the properties of a biophotonic sensor as above. First, the transmittance spectrum and/or the reflectivity spectrum of the biophotonic sensor prior to an antigen-antibody reaction are measured. The measured value is compared with the transmittance spectrum and/or the reflectivity spectrum of the biophotonic sensor after the antigen-antibody reaction. The comparison result is used as a basis to determine whether or not a specific antigen is present and to measure the concentration of the antigen if present.
FIG. 1 is a construction view illustrating an example of conventional measuring system having a biophotonic sensor, which measures a transmittance spectrum using a tunable light source. Referring to FIG. 1, the conventional measuring system includes a wavelength tuner 101, a tunable light source 102, a lens 103, a biophotonic sensor 104 and a photodiode 105.
The conventional measuring system converts light from the tunable light source 102 into parallel light using the lens 103. When the parallel light transmits the biophotonic sensor 104, the conventional measuring system detects the light at the photodiode 105, thereby measuring the transmittance spectrum of the biophotonic sensor 104. The intensity and the wavelength of the light outputted from the tunable light source 102 are tuned by the wavelength tuner 101. In the biophotonic sensor 104, an antibody of an antigen is immobilized, and an antigen-antibody reaction changes the transmittance of light.
Accordingly, this type of conventional measuring system measures the optical transmittance spectrum of the biophotonic sensor 104 with respect to the output wavelength of the tunable light source using the photodiode 105.
FIG. 2 is a construction view illustrating another example of conventional measuring system having a biophotonic sensor, which measures a reflectivity spectrum using a tunable light source. Referring to FIG. 2, the conventional measuring system includes a wavelength tuner 201, a tunable light source 202, a lens 203, a beam splitter 204, a bio-photonic sensor 205 and a photodiode 206.
The measuring system converts light from the tunable light source 202 into parallel light through the lens 203, and causes the parallel light to be reflected from the beam splitter 204 to the biophotonic sensor 205. The light reflected from the beam splitter 204 is reflected again from the biophotonic sensor 205 to the photodiode 206, which detects the intensity of the reflected light, thereby measuring the reflectivity of the beam splitter. The output wavelength of the tunable light source 202 is tuned by the wavelength tuner 201. In the biophotonic sensor 204, an antibody of an antigen is immobilized, and an antigen-antibody reaction changes the reflectivity spectrum of light.
Accordingly, this type of conventional measuring system measures the optical reflectivity spectrum of the biophotonic sensor 205 with respect to the output wavelength of the tunable light source 202 using the photodiode 206, acquires the difference in the wavelength of the biophotonic sensor 205 before and after the antigen-antibody reaction using the measurement result, and measures the concentration of the antigen.
FIG. 3 is graphs illustrating the transmittances and the reflectivity spectra of the typical biophotonic sensors 104 and 205, which are measured in the conventional measuring systems shown in FIGS. 1 and 2. Referring to FIG. 3, solid lines indicate the measurement results of the biophotonic sensors 104 and 205 before the antigen-antibody reaction, and dotted lines indicate the measurement results of the biophotonic sensors 104 and 205 after the antigen-antibody reaction. Accordingly, the concentration of the antigen is measured using the difference in the wavelength Δλ.
In the conventional measuring systems having a biophotonic sensor as mentioned above, the presence and the concentration of an antigen are determined using the variation of the transmittance spectrum and/or reflectivity spectrum before and after the antigen-antibody reaction. It is important to precisely measure an optical power and the wavelength thereof, which are applied to the biophotonic sensor. For this, there is required a device, such as a wavemeter, which measures the optical power and the wavelength thereof, applied to the biophotonic sensor. However, this type of wavelength-measuring device is bulky and thus is not adequate to be attached to a portable system.